How to get XML nodes using XPath expression?

To find nodes in an XML file we can use XPath expressions. System.Xml namespace provides following methods to retrieve nodes using xpath expression,

1. XmlNode.SelectNodes - returns a list of nodes selected by the xpath string.
2. XmlNode.SelectSingleNode – returns a first node that matches the xpath string.

We will write code using the following sample XML file.

<Employees>
  <Employee Gender=’F’>
    <Name>
        <FirstName>Aashi</FirstName>
        <LastName>Mishra</LastName>
    </Name>
  </Employee>
  <Employee Gender=’M’>
    <Name>
        <FirstName>Cameron</FirstName>
        <LastName>White</LastName>
    </Name>
  </Employee>
</Employees>

To get all nodes use xpath expression /Employees/Employee/Name. The first slash means that the node must be a root node. SelectNodes method returns collection XmlNodeList which will contain the nodes. To get value of sub node we can use index of XmlNode with the node name: node["FirstName"].InnerText. 

See the example below.

XmlDocument xml = new XmlDocument();

// xmlString contains the above mentioned xml data
xml.LoadXml(xmlString);
XmlNodeList nodes = xml.SelectNodes("/Employees/ Employee/Name");
foreach (XmlNode node in nodes)
{
  string firstName = node["FirstName"].InnerText;
  string lastName = node["LastName"].InnerText;
  Console.WriteLine("Employee Name: {0} {1}", firstName, lastName);
}

In the above example, we are retrieving values of XMLElement. Similar way, we can get data of XMLAttribute using xpath expression. 

Here I will give an example to get values of Gender attribute, /Employees/Employee/@Gender